Re: [PATCH 2/6] device/pci: add cmdmem cap to pci_dev

[Dave Jiang]

On 3/31/2020 3:04 AM, Greg KH wrote:
> On Mon, Mar 30, 2020 at 02:27:00PM -0700, Dave Jiang wrote:
> > Since the current accelerator devices do not have standard PCIe capability
> > enumeration for accepting ENQCMDS yet, for now an attribute of pdev->cmdmem has
> > been added to struct pci_dev.  Currently a PCI quirk must be used for the
> > devices that have such cap until the PCI cap is standardized. Add a helper
> > function to provide the check if a device supports the cmdmem capability.
> >
> > Such capability is expected to be added to PCIe device cap enumeration in
> > the future.
> >
> > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > ---
> >   drivers/base/core.c    |   13 +++++++++++++
> >   include/linux/device.h |    2 ++
> >   include/linux/pci.h    |    1 +
> >   3 files changed, 16 insertions(+)
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index dbb0f9130f42..cd9f5b040ed4 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -27,6 +27,7 @@
> >   #include <linux/netdevice.h>
> >   #include <linux/sched/signal.h>
> >   #include <linux/sysfs.h>
> > +#include <linux/pci.h>
> >   
> >   #include "base.h"
> >   #include "power/power.h"
> > @@ -3790,3 +3791,15 @@ int device_match_any(struct device *dev, const void *unused)
> >   	return 1;
> >   }
> >   EXPORT_SYMBOL_GPL(device_match_any);
> > +
> > +bool device_supports_cmdmem(struct device *dev)
> > +{
> > +	struct pci_dev *pdev;
> > +
> > +	if (!dev_is_pci(dev))
> > +		return false;
> > +
> > +	pdev = to_pci_dev(dev);
> > +	return pdev->cmdmem;
> > +}
> > +EXPORT_SYMBOL_GPL(device_supports_cmdmem);
> Why would a pci-specific function like this be ok to have in the driver
> core?  Please keep it in the pci core code instead.

The original thought was to introduce a new arch level memory mapping 
semantic. If you feel this should be PCI exclusive, should we make the 
ioremap routines for this memory type pci specific as well?


> thanks,
>
> greg k-h